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Home / Assemblies / UL D116
UL D1163-hr Fire RatingFloor/CeilingLoad-BearingSTC 39
Steel JoistGypsum BoardDesign

Steel Joist Floor/Ceiling — 3 layers 5/8" Type C gypsum board

UL-listed 3-hour fire-rated steel joist floor/ceiling assembly. Open-web steel joists at 24" o.c., 3 layers of 5/8" Type C gypsum board ceiling.

Cross-Section Diagram

123456FLOOR/CEILING ASSEMBLYSECTION · NOT TO SCALE6 LAYERSsee legend for ① ② ③
Legend
1Floor covering(varies)
23" concrete on steel deck(3")
3Open-web steel joists at 24" o.c.(14.0")
45/8" Type C gypsum board(5/8")
55/8" Type C gypsum board(5/8")
65/8" Type C gypsum board(5/8")

Specifications

Fire Rating
3-Hour
STC Rating
STC 39
Load Bearing
Yes
Total Thickness
17.38"
Source / Publisher
UL (Underwriters Laboratories)
Design Number
D116
Assembly Type
Floor/Ceiling
Test Standard
UL 263
Construction Group
Non-Combustible
Number of Layers
6 layers

Applicable Codes

IBC 2024 Table 722.1NFPA 5000IBC 2021 §722

Construction Summary

Open-web steel joists at 24" o.c., 3 layers of 5/8" Type C gypsum board ceiling

Material Layers

LayerMaterialThickness
1Floor coveringvaries
23" concrete on steel deck3"
3Open-web steel joists at 24" o.c.14.0"
45/8" Type C gypsum board5/8"
55/8" Type C gypsum board5/8"
65/8" Type C gypsum board5/8"

Important Notice

This assembly listing is for reference only. Always verify against the current UL Product iQ database before specifying in construction documents. Material substitutions may void the fire rating. Consult with a qualified fire protection engineer for project-specific requirements.